The purpose of this field project is to evaluate the epidemiological patterns and determinants of pediatric shigellosis occurring among residents in a research field site in rural Bangladesh who have had a documented recent exposure to a neighbor- hood resident having Shigella dysentery. 1934 children under 5 years of age, from 240 neighborhoods having a resident who presented for treatment of documented Shigella dysentery within 1 week of the initiation of active neighborhood surveil- lance, were assembled. Each of these children was followed with intensive active surveillance for one month, with a systematic schedule to ascertain symptomatic histories related to diarrhea, and to collect fecal specimens for microbiological characterization. Analyses have demonstrated that the occurrence of Shigella diarrhea was related to age (being highest in the third year of life), nutritional status (being higher in stunted children), season (being lowest during the monsoon season in the summer months), and breast-feeding status (being lower among breast-fed children, even up to 36 months of age). The presence of a latrine was not related to the risk, due to the fact that the presence of an unsanitary hanging latrine elevated the risk, while the presence of a sanitary latrine slightly depressed the risk. The lower risk of shigellosis in breast-fed than in non-breast fed children was almost entirely attributable to the increase in risk of shigrlosis which occurred during the initial 3 months following cessation of breast feeding. When host and environmental factors are considered conjointly as predictors of pediatric shigellosis, only nutritional stunting, age, and feeding mode dominate as risk factors. Vitamin A status was not related to the risk of shigellosis. Future analyses will focus on determinants of persistent diarrhea among Shigella-infected children.